RITHRODONTOMYS. 65 



interorbital constriction, 3. Ex type in United States National 

 Museum. 



4680. Rhithrodontomys amoenus Elliot. 



Rhithrodontomys amoenus Elliot, Proc. Biol. Soc. Wash., XVIII, 



IQOS, p. 234. 



Type locality. Reforma, State of Oaxaca, Mexico. 



Geogr. Distr. Known only from State of Oaxaca, Mexico. 



Genl. Char. Allied to R. helvolus but color different. 



Color. Fore part of back, cheeks and shoulders pale ochraceous- 

 buff ; top of head, lower part of back, rump and flanks dull ochraceous- 

 rufous, tinged with hazel; underparts, hands and feet white; tail 

 brownish above, white beneath. Ex type in Field Museum of Natural 

 History, Chicago. 



Measurements. Total length, 148; tail, Si; hind foot, 8.5. Skull: 

 Total length, 20; Hensel, 14; zygomatic width, 10; interorbital con- 

 striction, 3; palatal length, 8; length of nasals, 6; length of upper 

 molar series, 4; length of mandible, 12 ; length of lower molar series, 4. 

 Ex type in Field Museum of Natural History, Chicago. 



Rhithrodontomys megalotis nigrescens Howell. 



Reithrodontomys (!) megalotis nigrescens Howell, N. Am. Fauna, 

 1914, No. 36, p. 32. 



Type locality. Payette, Idaho. 



Geogr. Distr. Eastern Oregon and western Idaho; north to Pres- 

 cott, Washington, south to Bieber, California. 



Genl. Char. Similar to R. megalotis, but black above less buffy. 



Color. Summer Pelage. More brownish generally and less black 

 than in winter. 



Winter Pelage. Upperparts mixed black and pale ochraceous, 

 darkest on dorsal region ; buff lateral line indistinct ; tail above black- 

 ish brown, beneath white; underparts, hands and feet white; ears 

 hair-brown; hairs ochraoeous. Type in United States National 

 Museum. 



Rhithrodontomys amoles Howell. 



Reithrodontomys (!) amoles Howell, N. Am. Fauna, 1914, No. 36, 

 p. 40. 



Type locality. Phial de Amoles, Queretaro, Mexico. 



Genl. Char. Like R. m. saturatus but smaller; zygomata parallel; 

 bullse smaller, flatter. 



Color. Upperparts black and ochraceous-buff mixed; underparts 

 whitish, pectoral region tinged with ochraceous-buff; tail above fus- 



